This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from an application entitled Tension Mask and Frame Assembly for Color Cathode Ray Tube earlier filed in the Korean Industrial Property Office on Feb. 11, 2000, and there duly assigned Serial No. 2000-6542 by that Office.
1. Field of the Invention
The present invention relates to a color cathode-ray tube (CRT), and particularly, to a tension mask frame assembly for a cathode-ray tube that can reduce vibrations of a tension mask supported by a frame.
2. Description of the Background Art
In a color cathode-ray tube, three electron beams emitted from an electron gun pass through electron beam passing holes of a shadow mask having a color selection function. The electron gun is installed on a neck portion of a funnel. Then, the beams land on a fluorescent film formed on the inner surface of a panel which is coupled to the funnel forming a seal. The fluorescent film is coated with red, green and blue fluorescent substances and the fluorescent substances are excited by the incident beams, forming an image.
The above color cathode-ray tube needs to have a flat screen surface so that a viewing angle for a viewer can be wider and distortion of an image can be prevented. Accordingly, the mask installed inside the cathode-ray tube and having a color selection function should have a flat surface. However, such a flat mask is one of many obstacles in manufacturing a complete flat cathode-ray tube.
A tension mask frame assembly includes a frame and a flat type tension mask. The flat type tension mask has two long sides welded to the frame. A plurality of slits are formed in strips on the tension mask.
In the tension mask frame assembly having the above structure, since only the longer sides of the tension mask are secured to the frame, the shorter sides of the tension mask are free to vibrate in directions perpendicular to the surfaces of the tension mask. Thus, even a small impact applied from the outside can vibrate the tension mask supported by the frame. Such vibrations of the tension mask prohibit electron beams emitted from an electron gun from accurately passing through the slits. Accordingly, the paths of the electron beams having passed through the slits change so that an error in landing on each of portions of a fluorescent film is generated. As a result, an image displayed on a screen of the cathode-ray tube vibrates according to the vibrations of the tension mask so that the quality of the image deteriorates.
Exemplars of the art are U.S. Pat. No. 5,289,080 issued to Park for Mask Frame Damper for Color Cathode Ray Tubes, U.S. Pat. No. 6,054,803 issued to Saita for Color Selecting Mechanism for a CRT Having Specified Aperture Slit Dimensional Relationships in Order to Dampen Vibrations, U.S. Pat. No. 5,451,833 issued to Tong for Shadow Mask Damping for Color CRT, U.S. Pat. No. 5,598,938 issued to Kim et al for Frame Structure for a Cathode-Ray Tube, U.S. Pat. No. 4,798,992 issued to Ichigaya et al. for Color Cathode-Ray Tube with Electron Beam Selection Mask Support Structure, U.S. Pat. No. 5,949,183 issued to Saita et al. for Color Selecting Mechanism of Cathode-Ray Tube and Color Selecting Mechanism Frame Thereof, U.S. Pat. No. 4,605,879 issued to Rath for Rigid CRT Shadow Mask Assembly, and U.S. Pat. No. 4,847,532 issued to Rath for Tensed Shadow Mask Assembly for Cathode-Ray Tube.
It is therefore an object of the present invention to provide a tension mask frame assembly for a cathode-ray tube that prevents the tension mask supported at the frame from vibrating by an external impact so that deterioration of the quality of an image due to vibrations of the image can be prevented.
It is another object to have a mask in an electron beam apparatus that is stable and avoids vibrations that affect picture quality.
It is yet another object to have a tension mask that is easy to assemble and manufacture while still reducing the affects of vibration upon an image generated by the cathode-ray tube.
It is still yet another object to have a tension mask assembly that is inexpensive to manufacture and yet reduces the vibration on the tension mask that deteriorates the quality of an image.
Accordingly, to achieve the above objectives, there is provided a tension mask frame assembly for a color cathode-ray tube having a frame including first and second support members separated a predetermined distance from each other, and at least a pair of elastic members for supporting the first and second support members, both end portions of each of the elastic members are secured to the first and second support members, a tension mask including a plurality of strips separated a predetermined distance from each other and forming slits, a plurality of tie bars disposed between the strips and connecting neighboring strips to divide slits, where longer side portions perpendicular to a lengthwise direction of the strips are secured to the first and second support members so that a tensile force is applied to the strips, and vibration prevention members having both end portions supported at the first and second support members, having a predetermined tensile force, and being in contact with shorter side portions of the tension mask in a direction parallel to the strips of the tension mask.
It is preferred in the present invention that the vibration prevention members are formed of bands having a predetermined width and thickness, and that the bands are provided with a plurality of contact means facilitating contact with the edge of the shorter side portion of the tension mask.
Dummy bridges extending from the neighboring strips in the corresponding directions are formed between the strips connected by the tie bar.